Diffusion baffle for oil heaters



1944- o. c. SCHAUBLE DIFFUSION BAFFLE FOR OIL HEATERS Filed Feb. 15, 1943 I INVENTOR 0 1 aj'fifllll ATT in? UNITED STATE Patented Nov. 21, 1944 DIFFUSION BAFFLE FOR OIL HEATERS Otto C. Schauble, Mount Kisco, N. Y., asslgnor to The Lummus Company, New York, N. Y., a corporation of Delaware Application February 15, 1943, Serial No. 475,958

4 Claims.

This invention relates to oil heaters and especially to an improved diffusion baflle structure for employment in a furnace in which hydrocarbon oils are subjected to heating for purposes of distillation, cracking, or the like. More particularly, the invention relates to a baflle structure devised for use in connection with an inverted type furnace such as that disclosed in my copending patent application, Serial No. 445,128, filed May 30, 1942. 1

In the furnace described in my copending application, horizontal oil-conducting tubing. forms the bottom of a combustion or radiant-heating chamber, and the combustion gases flow downwardly over this tubing and through the spaces therebetween to an underlying plenum chamber. My present invention is directed more particularly to the provision of a satisfactory baflle structure for obtaining increased heat transference from the flowing gases to this tubing.

The principal object of my invention is to provide an improved difiusion baflle for a furnace of the type described.

A further object of my invention is to provide a diifusion baifle for a furnace of the type described in my copending application, the individual elements of which can be formed, assembled, and associated with the furnace tubing so as to obtain a well-distributed flow of the combustion gases over such tubing.

Another-object of my invention is to provide a support for the baflle-forming elements for convenient suspension thereof from the horizontal tubing of my inverted type furnace and also for convenient installation of such elements entirely from the under side of the tubing.

Astill further object of my invention is to provide improved baiile-forming elements for my suspended diffusion baflle construction and to provide improved hanger elements designed for ready application to the tubing from the under sidethereof and also designed for ready support of the bathe-forming elements in operative relaconnection with the accompanying drawing, in

which:

Fig. 1 is a vertical longitudinal sectional view of 'a portion of an oil heater or furnace equipped with my improved diifusion bathe;

Fig. 2 is a perspective view of a portion of the I baflle structure and the individual elements there-- 'As described inmy copending application, be-

tween these chambers there are a horizontal row of spaced upper tubes l2 and a horizontal row of spaced lower'tubes l3 parallel to the upper tubes and in staggered relation thereto. Low transverse walls W extend upwardly from the bottom of chamber II for support of the tubes I2 and I; at intermediate points along their length and are provided with suitable openings through which such tubes extend. There are also tubes along the side walls of the chamber l0; but

these tubes, along with other details of the heater, are omitted'from the drawing in order to simplify the illustration. Oil to be heated for the desired purpose is conducted through such tubing in a suitable manner.

This heater is desirably heated by suitable gas burners or the like placed in the end walls thereof. In this manner, radiant heat is supplied to the horizontal rows of tubes I2 and I3 as well as to the side wall tubes (not shown) with the lower row of tubes [3 receiving considerably less radiant heat than the upper row of tubes 12. The resulting combustion gases, in this type of heater, pass downwardly over the rows of tubes I2 and I3 and through the plenum chamber to the stack (not shown). The utilization of the entire floor area of the heater as a gasexit from the combustion chamber thus provides a low-velocity gas flow past the horizontal rows of tubes, which flow is particularly desirable so as to avoid excessive heat transfer by convection to the tubes l2.

To avoid channeling of the gases as they flow past the tubes I2 and the resulting local overheating thereof, a diffusion baflle is desirably installed in this zone and is preferably positioned in operative relation to the lower tubes l3. Pasthe combustion gases therethrough. These pas sages are uniformly distributed throughout the battle and have an aggregate flow area less than the intertube area of the upper row of tubes. In this manner, the gases during their passage through this 'baflle are subjected to a pressure drop which causes these gases to flow substantially uniformly across the entire upper row of tubes. Uniform heating of tubes 12 is thereby accomplished. Furthermore, a high rate of heat transfer to tubes I3 is provided, and a greater heat absorption by these tubes is obtained.

According to my invention, I have provided an improved diffusion baflle structure particularly for use with my inverted type oil heater. This bafiie is supported by the lower tubes [3 and com prises an assembled structure designed to conduct the hot combustion gases in narrow streams from the chamber I0 around the lower quadrants of the tubes I3 into the underlying plenum chamber ll. of the baflle are formed of ceramic, .tile, or other refractory material. These parts include baflieforming elements; blocks, or plates H and hanger sages are provided in this baffle for the flow of the distance between the'center lines of adjacent tubes. The major dimension of the stem cross section is less than the width of the space between each pair of tubes. The width of the head corresponds to the minor dimension of the stem cross section so" that the .head width is materially less than the width of the intertube held against release from the tubes. This keying Preferably, all elements or parts elements l5 for supporting the blocks by suspen- 43 to support the blocks in an assembled structure,- v

Each block is approximately rectangular in plan, and its width-between the longer "edgesis desirably .slightly less than the distance between' the center lines of adjacent tubes 13-. The intermediate portion of these edges is recessed to provide the concave arcuate surfaces Ila, having a' radius exceedingthat of the. outer circumference, of the tubesl3.- The recessed surface is desirably. substantially concentric with the extereffect is assisted by the trough shape of the under side or the several blocks, which shape holds the foot projections 2| against lateral shifting. The blocks and hangers are so proportioned as to enable the hangers to support the blocks with the end ridges it of the blocksrelatively close to the lower quadrants of the tubes. Furthermore, the dimensions of thelrespective pieces are so proportioned that 'suflicient clearance for ready manipulation thereof'can be provided.

The hanger elements engage the under nal surface ofthe tubing. By means of this re- 1 cuatelj and have a radius substantially *cor'responding to that of the tubing so that they close-.

Rows of. the blocks and hangers extend along all of the intertube spaces between the walls W and between such walls and the end walls of the furnace. For support 0f the, end blocks of each feetjl. At*its opposite side, this hanger is flat throughout.- K

The blocksand the hangers are designed not only toprovide a diflusionb'aiiie having the desired'characteristics, but als0' for convenient assembly and attachmentto the tubing l3. Preferably, both the block and the hangers are in-' serted into place from the under side of the tubing l3. This procedure is followed inasmuch ash; is customary to install the two horizontal,

-. rows of tubing and the other tubes before placing ly fit thelower'ouadra'nts of adjacent tubes and serve-to position each block with respect thereto. a When each block-is in position, the tubes engaged thereb and the arcuate surfaces a together define long :narrow passages for conducting the hot combustion gases downwardly around the lower quadrants of the tubes. In order to permit free and ready flow of these gases from such pas.-

the required refractory material in position. In

this manner, the obstructing effect of the staggered upper row. of tubing is avoided. The insertion and installation of the diflusion bailie In installing each row ,of the baffle blocks, one

sages'into the underlying plenum chamber ll,

the lower edges 11 of therecessed portion of each block are also set back from the line of the ridges l6 so that adjacent blocks form a long narrowexit slot. The under side of each block is shaped from end to end like an inverted trough,

I and a narrow flat bottom surface i8 is provided.

The centralportion of the shorterlends of each v block are recessed to 'form' the notches-l9.

Each hanger l5 preferably comprises a verticalstem portion 20 of rectangular cross section,

flat horizontal foot portions 2l' extending in op-e posite directions-from the broad sides oi the stem,

and substantially. arcuate;.arm portions 2; di.

. verging-from'the upper. end of the stem in a verticalx-plsme at'rightangles to that of the foot.

portions. In efiect; these .arm-portions form an elongated head whose length exceeds the width of the space between the tubes l3. Preferably, the length of.this head i only slightly less than fromthe upper sideof tubing I3 is possible, however, but isnot desirable in view of the greater difliculties inherent in such procedure in view of the-construction of the inverted type furnace.

of the special hangers 23 is first operatively applied tothe' respective pair-of tubes IS. The insertion of the hanger is accomplished 'from the under side ofthetubing by disposing the elongated head of. the hanger lengthwise of the tubes.

inserting the hanger upwardly through the intertube space, and then rotating the hanger about 't'he'axis of the stem to dispose the head crosswise o! thetube andto permit it to rest upon furnace walll one tube blocks is next fitted upwardly against the adjacent lower quadrants of the pair of tubes and is then slid back along .the'tubes until its flat'bottom surface ll overlaps the foot projection 2| of the hanger and the stem of thehanfler, ntersthe notch It at that endof the block. first block, so'placed; is 'held imposition, and one of the hangers l5 is applied to the pair of tubes from the under side thereof in the same manner as: the hanger 23 and is slid back along the tubes until its stem enters the adjacent end notch l9 of. such block and one of its foot projections 2| is disposed beneath the under surface l8 of the block.

Another block is next placed against the tubes and slid back until one of its end notches receives the stem of the second hanger and its bottom surface overlaps the opposite foot projection 2| of the second hanger. Subsequent blocks and hangers are assembled in the same manner until there is space for only one more block at the end of 'the row. Another one of.

the end hangers 23 is then applied to the tubes and disposed fiat against the adjacent wall, and the final block is then engaged with the foot projection 2| of such hanger. For insertion of this final block, the previously placed blocks and hangers along the row are moved together; and, after insertion of this block, they are spread slightly apart so as to lengthen the row until the hanger l adjacent the final block is advanced far enough to have its stem engage the adjacent notch I9 of such block and the adjacent foot projection 2| of such hanger is engaged with the under side of this final block.

Of course, in the operation of assembling this difiusion baflie, the order of placing the blocks and hangers in position may be varied somewhat. For example, if desired, all of the required hangers may be applied to the tubes prior to applying the blocks thereto.

When it is necessary to dismantle the baflie or to remove a defective block or hanger, disassembling of the baflie is readily effected by merely forcing the blocks and hangers in the particular row closer together to thereby release one of the end blocks and hangers. Such end block and hanger may then be manipulated for removal from the tubes. Space is thereby provided for manipulation of the remaining blocks and hangers in the row for release of the desired element. Any one of the hangers is detachable by rotating it until its elongated head is disposed lengthwise of the intertube space and then lowering the hanger through such space.

The following example illustrates the application of my improved diffusion baflie assembly to the oil heater described in my copending application, Serial No. 445,128. In this case, the tubes l2 and I3 were 5 inches in outside diameter, and the distance between the center lines of adjacent tubes was 10 inches. .Each block was 12% inches long and 9% inches wide; and the amount of recess of surface Ma and edge II was inch. Notch l9 was 3 inches wide by 1 inch deep. Each hanger was 8% inches high, and the spread of its arm portions was 9% inches. The stem had dimensions of 3 inches by 2 inches in cross section, and the foot portions 2| were 1 inches long. For the complete assembly of the baflie, approximately 470 blocks I4, 420 hangers l5, and 315 hangers 23 were required.

It will be seen that this baflle is designedto obtain a distribution of the flow of hot combustion gases for maximum transfer of heat to the tubing and that the parts of the baffle are designed to greatly facilitate assembly and use. It will also be seen that the parts are simply and durablyw constructed and are designed to render their construction out of suitable refractory material entirely practicable.

Although I have described my invention in connection with an 011 heater, its application is not necessarily so limited; and it may be used in other types of furnaces. While I have disclosed a very satisfactory form and embodiment of my invention, it will be understood that the structure of the baffle may be modified and that it may be employed in services other than that disclosed without departing from the invention as defined in the appended claims.

I claim:

1. A bottom wall structure for a combustion chamber, comprising parallel fluid-conducting tubes horizontally spaced in a common plane; rows of refractory blocks applied to the under side of said tubes and arranged in the respective rows in endwise opposed relation in succession along the spaces between the tubes, each of said blocks extending laterally across its respective intertube space and having projections engaging lower quadrant portions only of the adjacent tubes, said projections being spaced along the tubes to permit downward passage of combustion gases in contact with the lower quadrant portions of the tubes for heating the fluid within the tubes and each of said blocks having a medially located notch in each end thereof; and supporting elements for said blocks and each comprising a rigid piece of ceramic material formed with a shank portion extending upwardly through said notches of opposed block ends, a head portion at the upper end of said shank elongated in form transversely of the shank and extending laterally from opposite sides of the shank and engaging the upper sides of adjacent tubes and foot portions at the lower end of said shank portion and engaging the under side of said opposed block ends to support the blocks, the width of said head portion and shank portion lengthwise of the tubing being less than the width of the intertube space and the length of the head transversely of the tubing exceeding the width of the intertube space to enable application of the element to the tubes by disposal of the element with its head portion lengthwise of the tubes, insertion of the element upwardly through the intertube space and rotation of the element to dispose the head crosswise of the tubes.

2. A wall structure for a heating chamber, comprising parallel fluid-conducting tubes transversely spaced in a common plane; rows of refractory blocks applied to the under side of said tubes and arranged in the respective rows in endwise opposed relation in succession along the spaces between the tubes, each of said blocks extending laterally across its respective intertube space and engaging quadrant portions of the adjacent tubes located at one side only of said plane and each block having a medially located notch in each end thereof; and supporting elements for said blocks and each comprising a rigid piece of non-metallic refractory material formed with a shank portion extending through said notches of opposed block-ends, a head portion at one end of said shank elongated in form transversely of the shank and extending laterally from opposite sides of the shank to engage the sides of adjacent tubes at the opposite side of said plane and foot portions at the opposite end of said shank portion and engaging the opposed end portions of the blocks to support the blocks, the width of said head portion and shank portion lengthwise of the tubing being less than the width of the intertube space and the length of the head transversely of the tubing exceeding the width of the intertube space to enable application of the element to the tubes by disposal -01 the element with its head portion lengthwise of the tubes, insertion of the element through the intertube space from said opposite side of said plane and rotation of the element to dispose the head crosswise oi the tubes.

3. A wall structure for a heating chamber, comprising parallel fluid-conducting tubes transversely spaced in a common plane; rows of refractory blocks applied to the under side of said tubes and arranged in the respective rows in endwise opposed relationin succession along the spaces between the tubes, each of said blocks extending laterally across its respective intertube space and engaging quadrant portions of the adjacent tubes located at one side only of said plane and each block having a medially located notch in each end thereof; and supporting elements for. said blocks and each formed with a shank portion extending through said notches of opposed block ends, a head portion at one end of said shank elongated in form transversely of the shank and extending laterally from opposite sides of the shank engaging the sides of adjacent tubes at the opposite side of said plane and foot portions at the opposite end of said-shank portion and engaging the opposed end portions of the vblocks to support the blocks, the width of said head portion and shank portion lengthwise of the tubing being less than the width of the intertube space and the length of the head transversely of the tubing exceeding the width of the intertube space to enable applicationbf the element to the tubes by disposal oi-the element with its head portion lengthwise of the tubes, insertion of the element through the intertube space from said opposite .side of said plane and rotation of the element to dispose the head crosswise oi the tubes.

4. A wall structure for a heating chamber, as claimed in claim 3 and including supporting elements each having a shank portio and a head portion according to those of the supporting elements claimed in claim 3 and i a similar relation to the tubes and each having a single foot portion, said elements being located respectively at the ends of the rows of blocks, and said foot portion engaging the adjacent end block to support the latter.

O'I'IO C. SCI-IAUBLE. 

